Filling of fuel tanks or the like with gasoline or other liquids presents an ever-present hazard of spillage, either due to poor spout-to-opening control or when overfilling occurs in trying to completely fill the tank. In many such cases, the results are objectionable, either from safety considerations or environmental considerations. Eye-hand control of the filling procedure becomes quite difficult at the time the container becomes nearly full, as the visual warning between nearly full, full and over-full is quite short. A funnel-like filling device designed to greatly reduce these hazards, while allowing complete and rapid filling of a tank or other container with a flowable fluid, is desirable, and such would be particularly useful for use with lawnmowers, outboard engines for boats, kerosene heaters and the like.
More efficient funnels have been the object of many previous inventors who strove to accomplish the complete filling of a small container with a liquid without any spilling. U.S. Pat. No. 4,202,386 to Orr shows a funnel for guarding against overfilling which includes two vents which allow air to escape from the tank being filled. One of the vents is manually closed during the initial part of the filling and is then allowed to open after the lower entrance to the second vent becomes submerged during filling. U.S. Pat. No. 3,973,602 to Kruse shows a filling unit which has a very large bowl into which the gasoline or other liquid is poured, the volume of which is hopefully matched to the volume of the upper portion of the container being filled. A sealing arrangement is provided so that, once an air vent is blocked, further inflow of liquid into the tank is prevented, and after the bowl is filled to a predetermined level, disengagement of the funnel from the tank causes the seal to be broken hopefully allowing all of the liquid to be accommodated within and precisely fill the tank. These funnels have proven to be too slow or too cumbersome to be completely satisfactory. As a result, improved filling units continue to be desired.